The present invention relates to fire-fighting equipment, and more specifically to equipment coupled to a fire hose or pipeline for integrating an additive to a water stream.
Fire fighting systems typically include a fire truck, such as truck T in FIG. 1, which includes a pumping unit P that pumps water under high pressure from a tanker truck or a nearby fire hydrant, through a fire hose H1, H2 and nozzle N. While water alone is sufficient for most fires, some fires cannot be efficiently controlled or extinguished by water alone. In this case, certain chemical additives are introduced into the water line to be discharged onto the particular type of fire. Incidents involving flammable liquids or hazardous materials often require the use of a foam that is spread over the fire to starve the fire of oxygen or to suppress noxious vapors. For instance, Class A foam concentrates are used for wildland, rural and urban fire suppression on Class A fuels, such as wood, paper and other solid materials. Class B foam concentrates are primarily intended for Class B materials, such as flammable liquids containing hydrocarbons or polar solvents, and can be used for vapor suppression or extinguishment.
There are numerous approaches to introducing chemical additives or foam concentrates into the flow through firefighting water lines. Some systems utilize additive pumps for forced injection of the chemical into the water line. Such systems are generally complicated and are not portable. On the other hand, portable systems rely upon the movement of water through the fire hose to educe the chemical. In the context of the present invention, educe or induct means that liquid is drawn into the system, such as by the flow of another liquid. In one typical arrangement, a foam bucket F contains a liquid foam concentrate that is induced into the fire hose H2 by a foam eductor valve E. This typical eductor valve E relies upon venturi flow to draw the foam concentrate from the foam bucket F into the water stream passing through the eductor E.
The chemical additives or foam concentrates are often corrosive and usually expensive. Thus, the typical eductor valve E includes a check valve system to prevent backflow of water into the chemical supply. For instance, the by-pass eductor described in U.S. Pat. No. 5,960,887, includes a ball check valve integrated into a foam concentrate metering valve.
While the check valve is important to prevent water backflow, it can be problematic with respect to cleaning the eductor valve E. In fire-fighting equipment back-flow typically occurs when the discharge nozzle N is shut off or when the hose H2 is kinked so that fluid discharge is terminated. Without cleaning, the chemicals passing through the valve may congeal and foul the valve or the metering orifice used to control the quantity of chemical introduced into the water stream. In an extreme case, the valve may be stuck open or closed. Prior devices require disengaging the eductor valve from the water line, connecting the water supply hose H1 to the chemical inlet of the eductor valve E, and flushing the valve with water. This process is cumbersome, but perhaps more significantly this approach can be hazardous. In particular, disengaging a eductor valve filled with a chemical additive of foam concentrate will necessarily result in a chemical spill.
What is needed is an eductor valve apparatus that satisfies all of the necessary functions of an eductor, but that is easy and safe to clean. Such an apparatus would allow controlled flushing so that the chemicals can be safely collected without risk of spilling. A further need is the ability to readily determine the position of the check valve and to manually alter it.